Anisotropic Atomic Hydrogen Distribution in Interplanetary Space

Blum and Farr 1 have suggested modifications of current theories 2,3 concerning the interaction of the solar wind with interstellar hydrogen. One feature of their model involves the motion of the solar system. This motion, coupled with the velocity of the interstellar hydrogen, results in a velocity of 10 to 40 km s −1 for interstellar hydrogen relative to the solar system. According to Blum and Fahr the relative velocity gives rise to an anisotropic distribution of neutral hydrogen atoms in interplanetary space. The neutral hydrogen density is enhanced in the direction of approach of the interstellar hydrogen and diminished in the opposite hemisphere. The motion of the interstellar hydrogen is assumed to cause a highly aspherical transition region between the hydrogen and the solar wind.